1. Field of the Invention
The present invention relates generally to clutches for connecting and disconnecting driving members and driven members so as to connect and disconnect the driving force in machines such as mechanical presses and, more particularly, the invention relates to what is called multiple-disk clutches having a plurality of disks for connecting and disconnecting the driving and driven members.
2. Description of the Prior Art
As is well-known, clutches having disks and often referred to as multiple-disk clutches are used to connect and disconnect driving members and driven members so as to connect and disconnect driving members and driven members to connect and disconnect the driving force in machines such as mechanical presses mostly in a manner such that working parts are bathed in oil during operation. Summarily stated, the clutches of this type have an input shaft radially provided with a plurality of axially movable disks and an output shaft which is disposed in coaxial relation with the input shaft and also have a plurality of axially movable disks disposed in engagement with the disks of the input shaft. More particularly, the arrangement is that each of the disks of the input shaft is disposed between a respective pair of the disks of the output shaft and all the disks of both of the shafts are axially movable but are not rotatable with respect to the shafts. Thus, the clutches of this type are so arranged as to connect the driving members by the friction of the disks and the driven members when the disks of both of the shafts are axially pressed and also disconnect them when the disks are released from the pressure. In this arrangement, the input shaft and the output shaft are conventionally journaled in thrust bearings to cope with the thrust load which occurs and acts when the disks are axially pressed to connect and disconnect the driving members and the driven members.
In the above described conventional multiple-disk clutches, one of the disadvantages has been that a high degree of heat will occur during operation. In wet multiple-disk clutches in which the working members are lubricated and cooled by oil, the heat will be produced to the extent that the oil temperature goes up to 50.degree. C. above the atmospheric temperature and often up to about 80.degree. C. in the summertime in mechanical presses. A high degree of heat produced in multiple-disk clutches mounted in a mechanical press, for instance, will be conducted to and deform the frame of the press and injure the processing accuracy of the press.
The undesirable heat in the multiple-disk clutches is produced from the thrust bearings among others because of the thrust load when the disks of the input shaft and the output shaft are axially pressed to connect and disconnect the driving and driven members. Thus, in order to reduce the heat in the multiple-disk clutches, it is desired that the thrust load be eliminated when the driving and driven members are connected and disconnected with each other. Furthermore, it is desired to eliminate the thrust bearings from the multiple-disk clutches, since the thrust bearings are costly and subject to wear and damage as compared with radial bearings.